1. Field of the Invention
The present invention relates to a single-lens reflex camera having data-transmission pins (contact members) at positions other than on the lens mount surface thereof; and in particular, to a photographic lens, a camera body and a camera system of a medium-format single-lens reflex camera.
2. Description of the Related Art
In single-lens reflex cameras of the prior art, a contact pin group (a lens pin group) at a position other than the lens mount surface of the photographic lens thereof has been provided (for example at an inside part of the lens mount surface) having a plurality of contact pins in order to identify open aperture data and minimum aperture data. A corresponding contact pin group (body pin group) having a plurality of contact pins which make contact with the lens pin group is provided in the vicinity of a lens mount surface of the camera body. The electric potential (level) at these contact pin groups are checked; subsequently, the open aperture data and the minimum aperture data are input in the camera body.
Recently, there has been requirements for functions that are not provided in photographic lenses or camera bodies of the prior art. However, when a photographic lens or a camera body is to be equipped with additional new functions, there arises a problem of compatibility between pre-existing and new photographic lenses or camera bodies; in particular, the compatibility of the contact members and the communication system which carries out data transmission between the photographic lens and the camera body.
FIGS. 4 and 5 are examples of lens mounts of a photographic lens and a camera body of the prior art. The aperture data setting pin group (a contact pin group) includes a series of lens pins 75a, 75b, 75c, 75d, 75j, 75k and 75l. The lens pins 75a through 75d and 75j through 75l are aligned in a circle, the center of which lies on the optical axis of photographic lens 71 closer to the optical axis than mount ring 72 and bayonet plate 73 (i.e., inside the concentric circles of the mount ring 72 and the bayonet plate 73) of the photographic lens 71. The aperture data is transmitted from the lens pins 75a, 75b, 75c, 75d, 75j, 75k and 75l to corresponding body pins 55a, 55b, 55c, 55d, 55j,55k and 55l, which serve as data-transmission pins, in order to be read by a camera body 51. The body pins 55a through 55d and 55j through 55lare also aligned in a circle, the center of which lies on the optical axis of the camera body 51, closer to the optical axis than mount ring 52 or bayonet plate 53 (i.e., inside the concentric circles of the mount ring 52 and the bayonet plate 53) of the camera body 51. Each of the lens pins 75a through 75d and 75j through 75lis fixed on a protection ring 74 made of an insulating material, each protruding from each hole therefor formed in the protection ring 74. Each of the body pins 55a through 55d and 55j through 55lis also fixed on a pin supporting plate 56 made of an insulating material, each protruding from each hole therefor formed in the pin protection plate 56. A spring force is applied to each of the body pins 55a through 55d and 55j through 55lby a spring (not shown), whereby the body pins 55a through 55d and 55j through 55lcan protrude from the pin supporting plate 56 or sink therein. Furthermore, the mount ring 52 and the bayonet plate 53 of the camera body 51 and the mount ring 72 and bayonet plate 73 of the photographic lens 71 are all formed from metal. Consequently, when the photographic lens 71 is attached to the camera body 51, each mount ring (72 and 52 respectively) and each bayonet plate (73 and 53 respectively) make contact with each other, wherein the electric potential level thereof becomes the same as ground.
However, when the above-mentioned photographic lens is equipped with new functions such as ROM, an AF motor and a controller therefor, or a lens shutter and a controller therefor; sufficient data or command communication relating to such new functions cannot be carried out using pre-existing, former lens pins 75a through 75d and 75j through 75land body pins 55a through 55d and 55j through 55l. Furthermore, though a new-designed photographic lens having additional lens pins can be matched with a new-designed camera body also having additional body pins, if such a new (designed) photographic lens having additional lens pins is attached to a pre-existing camera body, the additional lens pins cannot make contact with any member of the pre-existing camera body. Therefore it is impossible to carry out data or command communication between the new photographic lens and the pre-existing camera body. In other words, the pre-existing camera body cannot recognize the new commands of the new photographic lens.
Further, if the photographic lens incorporates a control device such as a CPU, or if the photographic lens does not incorporate the control device such as a CPU but incorporates a lens data memory such as a ROM, it is necessary to firstly identify whether the attached photographic lens is a ROM-incorporated lens or a CPU-incorporated lens. However, as compared with the data loading time from the ROM, the CPU requires a longer start-up time before executing the program after the power is turned ON. Thus, a longer time is required to identify the type of photographic lens attached to the camera body.
It is an object of the present invention to provide a photographic lens, a camera body and a camera system, each of which can immediately identify whether the photographic lens attached to the camera body incorporates a memory or a control device.
To achieve the object mentioned above, according to the present invention, there is provided a camera body in which, when a photographic lens is attached to the camera body, data exchange is carried out by communicating with the photographic lens via a plurality of contact pins electrically connected to each other. The camera body includes: a reset pin as one of the contact pins which outputs a reset signal and a reset release signal; and an identifying pin as another of the contact pins for identifying an attached photographic lens.
Preferably, an identifying device is provided which identifies an attached photographic lens according to the change of electric potential of the identifying pin upon the output of the reset release signal to the reset pin.
Preferably, whether or not the electric potential of the identifying pin changes is detected immediately after the output of the reset release signal to the reset pin; and when a change of electric potential is detected, the identifying device identifies that an attached photographic lens incorporates a memory.
Preferably, the reset signal is firstly output to the reset pin, then whether or not the electric potential of the identifying pin changes is detected by the output of the reset release signal to the reset pin; and when a change of electric potential level is detected, the identifying device identifies that an attached photographic lens incorporates a control device.
According to another aspect of the present invention, there is provided a photographic lens including a plurality of contact pins including a reset pin and an identifying pin; wherein data communication is carried out via contact of the contact pins when the photographic lens is attached to a camera body, the photographic lens includes: a memory not including a control device; and a response device in which, when the reset pin receives a reset release signal from the camera body, the electric potential of the identifying pin changes.
Preferably, when the reset release signal is applied to the reset pin, the response device is synchronized with a clock input from the camera body via a data pin other than the reset pin or the identifying pin, wherein data recorded in the memory is converted to serial data output from the identifying pin.
According to another aspect of the present invention, there is provided a camera system which includes a photographic lens and a camera body respectively having a plurality of contact pins including a reset pin and an identifying pin; wherein data communication is carried out via contact of the contact pins when the photographic lens is attached to the camera body. If the photographic lens incorporating a memory does not include a control device, the photographic lens further includes a response device in which the electric potential level of the identifying pin changes when the reset pin of the photographic lens receives a reset release signal from the camera body; and the camera further including an identifying device which identifies whether or not an attached photographic lens incorporates the memory, by detecting the change of electric potential of the identifying pin through the output of the reset release signal to the reset pin of the camera body.
Preferably, if the photographic lens includes the control device, upon output of the reset release signal from the camera body to the reset pin, the electric potential of one predetermined contact pin of the plurality of contact pins, that is not the reset pin of the photographic lens, falls once and then rises; wherein the camera body identifies that an attached photographic lens includes the control device by detecting the change of electric potential of the one predetermined contact pin.
Preferably, data loading is carried out by serial communication via the identifying pin from the memory when the identifying device identifies that an attached photographic lens includes the memory.
Preferably, the identifying pin of the photographic lens incorporating the memory also serves as a data pin when the reset release signal is input to the reset pin; wherein data read from the memory, according to clock output from the camera body, are output to the camera body.
The present disclosure relates to subject matter contained in Japanese Patent Application No.09-336029 (filed on Dec. 5, 1997) which is expressly incorporated herein by reference in its entirety.